47.18 MoebiusTom

MoebiusTom( tom )

MoebiusTom computes the Maccent127 obius values both of the subgroup lattice of the group with table of marks tom and of the poset of conjugacy classes of subgroups. It returns a record where the component mu contains the Maccent127 obius values of the subgroup lattice, and the component nu contains the Maccent127 obius values of the poset. Moreover, according to a conjecture of Isaacs et al. (see HIO89, Pah93), the values on the poset of conjugacy classes are derived from those of the subgroup lattice. These theoretical values are returned in the component ex. For that computation, the derived subgroup must be known in the component derivedSubgroup of tom. The numbers of those subgroups where the theoretical value does not coincide with the actual value are returned in the component hyp.

    gap> MoebiusTom( a5 );
    rec(
      mu := [ -60, 4, 2,,, -1, -1, -1, 1 ],
      nu := [ -1, 2, 1,,, -1, -1, -1, 1 ],
      ex := [ -60, 4, 2,,, -1, -1, -1, 1 ],
      hyp := [  ] ) 

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GAP 3.4.4
April 1997